Disposal of spent fuel in Finland

Finland has been running a long-term research and development programme aimed at the implementation of high-level nuclear waste disposal. The disposal facility has progressed to a stage where Posiva Oy filed a construction licence application to the Ministry of Employment at the end of 2012,and the Economy and the licence has been granted by the Government at the Ministry’s proposal in 2015. The principle is that the disposal must not cause any harmful radiation exposure to people or the environment.

The schedule for preparation of spent nuclear fuel for disposal was defined in a Government decision in 1983. In accordance with the objectives set in the decision, the site for disposal should be selected by the end of 2000, the construction of the disposal facility should be started at the beginning of the 2010s and disposal should begin around 2020.

Teollisuuden Voima Oyj and Posiva Oy conducted research aimed at the selection of the disposal site at six locations in Finland in the 1990s, and in 1999, Posiva proposed Olkiluoto in the municipality of Eurajoki as the location of the final depository in their application for a decision-in-principle. In the application for a decision-in-principle, the intended disposal concept (KBS-3) was also presented. The aim is to encapsulate the used nuclear fuel in copper canisters and dispose of them, surrounded by bentonite clay, in premises built into bedrock at a depth of 400–450 metres.

In May 2001, the Finnish Parliament ratified the decision-in-principle to build a disposal facility for spent nuclear fuel at Olkiluoto in Eurajoki.

In October 2003, the Ministry of Employment and the Economy decided to revise the original schedule, so that the construction licence application was to be ready by the end of 2012.

Posiva submitted an application for a construction licence concerning an encapsulation and disposal facility for spent nuclear fuel to the Ministry of Employment and the Economy at the end of 2012. STUK gave its statement on the application at the beginning of 2015. The licence was granted by the Government at the proposal of the Ministry of Employment and the Economy late in 2015.

Encapsulation and disposal facility

For the disposal of spent fuel, an above-ground encapsulation facility and an underground disposal facility are needed. In the above-ground encapsulation facility, nuclear fuel that has been in interim storage for 30–50 years is received, dried and packed into final disposal canisters.

The disposal facility consists of facilities for the disposal of waste packages (repository) and related underground and above-ground auxiliary facilities. The encapsulation facility (above-ground) and disposal facility (underground) are connected to each other with an elevator shaft and canister transfer shaft as well as a separate access tunnel. In the processing of nuclear waste, mainly equipment operated by remote control is used.

The disposal facility consists of an access tunnel that reaches a depth of approximately 450 metres, technical facilities located at a depth of 437 metres and central tunnels and disposal tunnels to be built in phases during the facility’s use. Since 2004, Posiva has been building an underground research facility, called Onkalo, the premises of which are designed to function as part of the disposal facility.

The disposal system is composed of a tightly sealed iron-copper canister, a bentonite buffer enclosing the canister, a tunnel backfilling material made of expansive clay, the sealing structures for the tunnels and premises and the enclosing rock.

Radiation and Nuclear Safety Authority (STUK) supervises radiation and nuclear safety in Finland. The purpose of STUK is to protect people, society, the environment and future generations from the detrimental effects of radiation.